Your Favorite Watershed - Watershed Assessment Report
Carl Schwarz
2017-05-06
1 Background
“How are the fish in my river and streams doing?” We need this answer to set appropriate fishing regulations, to understand and correct any problems with fish habitat and to guard against invasive species.
A healthy fish population and fish community means we can all enjoy the benefits of sustainable fisheries and healthy ecosystems. A standard method of assessing the status of fish populations is necessary to allow comparisons of fish sustainability across the years in a watershed, and to compare to other watersheds in the province. In Alberta, we use accepted standard sampling methods for watershed fisheries assessments. These methods provide the necessary data on fish abundance, biological data (such as genetic information, age and sex), and species diversity to assess sustainability over time and space.
2 Watershed Assessments
Alberta Environment and Parks monitor fish in flowing waters using standardized electrofishing and habitat surveys techniques. Surveys often occur during the summer when river and stream flows are lower to allow for safe working conditions and high visibility of observed fish. Although information is collected from all species, assessments often focus on species such as Westslope Cutthroat Trout (Oncorhynchus clarkii lewisi), Bull Trout (Salvelinus confluentus), Arctic Grayling (Thymallus arcticus), Athabasca Rainbow Trout (Oncorhynchus mykiss), and Mountain Whitefish (Prosopium williamsoni).
Watersheds are defined by the Hydrologic Unit Code (HUC) 10 watershed boundary, as identified by the HUC Watersheds of Alberta system of classification system (reference? AB or USGS?). Within the study area, 999999999 potential sampling locations were randomly chosen using ArcGIS (ESRI, 2013) and R (R Core Team, 2015) using generalized random tessellation stratified (GRTS) sampling (Stevens and Olsen, 2004; Reilly, 2016). Sites were further removed from consideration if they were observed or strongly suspected to be dry or if there were access limitations that prevented crews from reaching the sites. In total, 65 sites were sampled in the Freeman Huc8 watershed as shown on the Figure 1.
The set of unique TTM co-ordinates for the plot above are:
## TTM.Easting TTM.Northing Longitude Latitude
## 472263.2 6041005 -115.4289 54.53761
## 463220.9 6045846 -115.5693 54.58055
## 463383.8 6045283 -115.5667 54.57550
## 463398.7 6046369 -115.5666 54.58526
## 463408.3 6046179 -115.5664 54.58356
## 486541.5 6048285 -115.2084 54.60364
## 486524.8 6048543 -115.2087 54.60596
## 454167.4 6043312 -115.7090 54.55704
## 457760.6 6041006 -115.6531 54.53662
## 457579.5 6040969 -115.6559 54.53626
## 448111.0 6042553 -115.8025 54.54962
## 447933.7 6042399 -115.8052 54.54822
## 451668.5 6049144 -115.7486 54.60923
## 451619.8 6049367 -115.7494 54.61122
## 449349.4 6048155 -115.7843 54.60011
## 449152.1 6048248 -115.7874 54.60093
## 449821.7 6045177 -115.7765 54.57339
## 449685.0 6045048 -115.7786 54.57221
## 450805.2 6045162 -115.7613 54.57335
## 450805.7 6045040 -115.7613 54.57225
## 447362.7 6044928 -115.8145 54.57090
## 447114.0 6045081 -115.8184 54.57225
## 443546.2 6057940 -115.8761 54.68746
## 443376.0 6058036 -115.8788 54.68830
## 438611.6 6051491 -115.9513 54.62891
## 438459.6 6051347 -115.9536 54.62760
## 440054.9 6053607 -115.9294 54.64810
## 439864.4 6053379 -115.9323 54.64603
## 446390.0 6058738 -115.8321 54.69494
## 442901.5 6051383 -115.8848 54.62844
## 447239.7 6054414 -115.8181 54.65616
## 447239.2 6054431 -115.8182 54.65631
## 466614.5 6042470 -115.5164 54.55044
## 441454.6 6053880 -115.9077 54.65072
## 441321.9 6054100 -115.9098 54.65268
## 465381.5 6047491 -115.5360 54.59549
## 465126.2 6047410 -115.5400 54.59475
## 474745.6 6058496 -115.3920 54.69499
## 464171.9 6059670 -115.5562 54.70490
## 468884.3 6054379 -115.4825 54.65765
## 463211.5 6045926 -115.5694 54.58127
## 469941.5 6038422 -115.4645 54.51425
## 465525.2 6044258 -115.5334 54.56644
## 481757.1 6043795 -115.2822 54.56313
## 449461.9 6043557 -115.7818 54.55878
## 453665.3 6042678 -115.7167 54.55129
## 443312.5 6053388 -115.8788 54.64651
## 440944.8 6063340 -115.9176 54.73570
## 449238.8 6058143 -115.7878 54.68989
## 472427.1 6060618 -115.4282 54.71395
## 447792.9 6056202 -115.8099 54.67229
## 467567.0 6047738 -115.5022 54.59786
## 467586.0 6057919 -115.5030 54.68939
## 487733.3 6045790 -115.1899 54.58124
## 487249.8 6050503 -115.1976 54.62360
## 436048.8 6055541 -115.9919 54.66500
## 436046.7 6055542 -115.9919 54.66501
## 438179.6 6057600 -115.9593 54.68377
## 454722.2 6049122 -115.7013 54.60932
## 450511.4 6060271 -115.7684 54.70914
## 453390.1 6061129 -115.7239 54.71713
## 455779.4 6044527 -115.6842 54.56809
## 479465.4 6053373 -115.3184 54.64914
## 495817.8 6039506 -115.0646 54.52487
## 474245.0 6049843 -115.3990 54.61717Fish sampling protocols followed existing flowing water fish survey standards.Specifically, we used backpack or boat electrofishing to capture fish in wadeable streams and rivers respectively. Sampling effort was recorded and fish were measured. If required, fin clips were taken for genetic analyses.
2.1 How is this information used?
Catch rates (i.e., backpack electrofishing: number of fish per 300 meters, boat electrofishing: number of fish per 1 km) of fish species are an index of the populations’ abundance, with higher catch rates meaning there are more fish in a stream or river. The sizes and age of fish also tell us if problems with overharvest (e.g. too few fish living to old age) or habitat (e.g., poor spawning success) are a concern. Biologists use this information, as well as a variety of data on water quality, access, development, and habitat threats as part of Alberta’s Fish Sustainability Index (FSI) and evaluation of species recovery work.
3 Results
Fish and habitat sampling was conducted at 65 sites within the Freeman Huc8 (HUC 17010603) from 2008-05-20 to 2015-08-21. This watershed is found approximately 999999999 km northwest from the city of Calgary.
There were 16 species of fish were captured over this period and the mean fork length, size range, and mean catch rates for all captured fish over this period are summarized in Table 1.
| Species Code | n | Mean fork length mm | Min fork length mm | Max fork length mm |
|---|---|---|---|---|
| ARGR | 163 | 101 | 46 | 282 |
| BKTR | 7 | 159 | 98 | 219 |
| BRST | 84 | 61 | 51 | 69 |
| BURB | 233 | 148 | 41 | 350 |
| EMSH | 5 | 53 | 45 | 60 |
| FNDC | 4 | 74 | 68 | 80 |
| LKCH | 698 | 73 | 24 | 200 |
| LNDC | 91 | 69 | 32 | 182 |
| LNSC | 50 | 109 | 39 | 221 |
| NNST | 4 | 56 | 53 | 60 |
| NRDC | 1 | 48 | 48 | 48 |
| PRDC | 83 | 65 | 35 | 97 |
| RNTR | 180 | 121 | 29 | 256 |
| SPSC | 62 | 83 | 40 | 117 |
| TRPR | 83 | 58 | 23 | 96 |
| WHSC | 133 | 102 | 37 | 257 |
Catch per unit effort (CPUE) was computed for each species for each year as follows:
- The distance sampled (m) and count by species was extracted for each Inventory Survey ID.
- The distance sampled and count by species were summed over multiple Inventory Survey IDs for a location. A location was defined by the combination of TTM Easting and TTM Northing.
- The CPUE was computed as total count / total distance \(\times\) 300 m to standardize to a per 300 m basis.
A Bayesian analysis was used to compute the posterior probability of belonging to each FIS Category based on the yearly trend in the median CPUE accounting for within-year sampling variation, site-to-site random variation, and year-specific effects (process error) as described in Schwarz (2017).
In the following sections, a more detailed investigation of the status of each of the above species will be provided.
3.1 ARGR
The mean fork length and size range for this species on a yearly basis are summarized in Table 2 and plotted in Figure 2.
| Year | n | Mean fork length mm | Min fork length mm | Max fork length mm |
|---|---|---|---|---|
| 2008 | 125 | 101 | 46 | 282 |
| 2015 | 38 | 100 | 62 | 200 |
The length distribution over all years is shown in Figure 3. Black vertical line indicates estimated length at 50% maturity (999999999999 mm Fork Length). {Not yet shown –How is this known from the data? }
A plot of the CPUE over time is shown in Figure 4.
With only two years of data, a trend line could not be computed. The Bayesian analysis assumed that there was no change in the median response between the two years to estimate process error and the probability of belonging to each FSI category.
Plots of the posterior distribution of the median and the FSI Category membership are shown in Figure 5 and Figure 6.
3.2 BURB
The mean fork length and size range for this species on a yearly basis are summarized in Table 3 and plotted in Figure 7.
| Year | n | Mean fork length mm | Min fork length mm | Max fork length mm |
|---|---|---|---|---|
| 2008 | 121 | 148 | 41 | 350 |
| 2015 | 112 | NA | NA | NA |
The length distribution over all years is shown in Figure 8. Black vertical line indicates estimated length at 50% maturity (999999999999 mm Fork Length). {Not yet shown –How is this known from the data? }
A plot of the CPUE over time is shown in Figure 9.
With only two years of data, a trend line could not be computed. The Bayesian analysis assumed that there was no change in the median response between the two years to estimate process error and the probability of belonging to each FSI category.
Plots of the posterior distribution of the median and the FSI Category membership are shown in Figure 10 and Figure 11.
3.3 RNTR
The mean fork length and size range for this species on a yearly basis are summarized in Table 4 and plotted in Figure 12.
| Year | n | Mean fork length mm | Min fork length mm | Max fork length mm |
|---|---|---|---|---|
| 2008 | 149 | 118 | 29 | 246 |
| 2015 | 31 | 134 | 32 | 256 |
The length distribution over all years is shown in Figure 13. Black vertical line indicates estimated length at 50% maturity (999999999999 mm Fork Length). {Not yet shown –How is this known from the data? }
A plot of the CPUE over time is shown in Figure 14.
With only two years of data, a trend line could not be computed. The Bayesian analysis assumed that there was no change in the median response between the two years to estimate process error and the probability of belonging to each FSI category.
Plots of the posterior distribution of the median and the FSI Category membership are shown in Figure 15 and Figure 16.
4 Summary
Describe where fish are found in the watershed (general statement for all game fish species) For each game species interpret the catch rate and size distribution. What does this mean for the population? Did any environmental factors potentially influence assessment e.g. flood? What kind of conservation actions need to be taken?
5 References
Alberta Biodiversity Monitoring Institute and Alberta Sustainable Resource Development (ABMI and ASRD). 2014.
Fish Survey Methods for Rivers: ABMI and ASRD Collaboration. Written by Jim Schiek and edited by M.G. Sullivan. Prepared for Alberta Biodiversity Monitoring Institute andAlberta Sustainable Resource Development. 20 pp.
Alberta Fisheries Management Branch. 2013. Standard for sampling of small streams in Alberta. Alberta Environment and Sustainable Resource Development, Fisheries Management Standards Committee. 19 pp.
Environmental Systems Research Institute (ESRI). 2013. ArcGIS Desktop: Version 10.2. Redlands , CA: Environmental Systems Research Institute.
R Core Team. 2015. R: A language and environment for statistical computing. R Foundation forStatistical Computing, Vienna, Austria. URL (http://www.R-project.org/.
Mackay, W.C., G.R. Ash, H.J. Norris. 1990. Fish ageing methods for Alberta. R.L. & L. Environmental Services Ltd. In assoc. with Alberta Fish and Wildlife Division and University of Alberta, Edmonton. 113 pp.
Microsoft Corporation. 2010. Microsoft Excel, version 14.0.7145.5000.
Part of Microsoft Office Professional Plus 2010. Redmond Washington.
Reilly, J. 2016. GRTS: User friendly method for busy biologists. Alberta Environment and Parks. 4 pp.
Schwarz, C.J. 2017. Bayesian classification into the Alberta FWIS Categories. Unpublished report.
Statistical Analysis Software (SAS) Institute Inc. 2016. JMP Statistical Discovery, version 13.0.0. SAS Campus Drive, Cary, North Carolina 27513, USA.
Slipke, J.W. 2010. Fishery Analyses and Modeling Simulator (FAMS). Version 1.0.
Alberta Sustainable Resource Development (ASRD). 2008. Electrofishing Certification and Safety Standard. Alberta Sustainable Resource Development, Fish and Wildlife Division. Edmonton, AB. 76 pp.
Stevens, D.L., A.R. Olsen. 2004. Spatially balanced sampling of natural resources. Journal of the American Statistical Association 99(465):262-278.
Watkins, O.B., S.C. Spencer. 2009. Collection, preparation and ageing of walleye otoliths. Alberta Sustainable Resource Development, Fish and Wildlife Division. Spruce Grove, AB. 26 pp.